The Remarkable Effects Of Exercise On Cognition And Brain Cell Regeneration

By Dr. Mercola

Scientists have been linking physical exercise to
brain health for many years. In fact, compelling evidence shows that
physical exercise helps build a brain that not only resists shrinkage,
but increases cognitive abilities.1

For example, we now know that exercise promotes a process known as
neurogenesis, i.e. your brain’s ability to adapt and grow new brain
cells, regardless of your age.

The featured article in Real Simple magazine2 highlights a number of brain-boosting benefits of exercise, including the following.

Exercise Shields You from Stress and Depression

Exercise is one of the “secret weapons” to overcoming
depression, and studies have shown its efficiency typically surpasses
that of antidepressant drugs. In fact, research has shown that in most cases these drugswork no better than a placebo – and can also have serious side effects.

One of the ways exercise promotes mental health is by normalizing
insulin resistance and boosting natural “feel good” hormones and
neurotransmitters associated with mood control, including endorphins,
serotonin, dopamine, glutamate, and GABA.

Swedish researchers3 have
also teased out the mechanism by which exercise helps reduce stress and
related depression. As it turns out, mice with well-trained muscles
have higher levels of an enzyme that helps metabolize a stress chemical
called kynurenine.

Their finding suggests that exercising your muscles actually helps
rid your body of stress chemicals that can lead to depression. According
to the authors:4

“Our initial research hypothesis was that trained
muscle would produce a substance with beneficial effects on the brain.
We actually found the opposite: well-trained muscle produces an enzyme
that purges the body of harmful substances. So in this context the
muscle’s function is reminiscent of that of the kidney or the liver.”

Recent research has also shown the clear links between inactivity and depression.
Women who sat for more than seven hours a day were found to have a 47
percent higher risk of depression than women who sat for four hours or
less per day. Those who didn’t participate in any physical activity at
all had a99 percent higher risk of developing depression than women who exercised.

To Boost Creativity, Get Moving!

As noted in the featured article, exercise can also boost
your creativity, and help you come up with new solutions to problems.
For example, researchers at Stanford University found that walking can
increase creativity up to 60 percent.5,6 Even a casual stroll around your office can be helpful.

“Four experiments demonstrate that walking boosts
creative ideation in real time and shortly after… Walking opens up the
free flow of ideas, and it is a simple and robust solution to the goals
of increasing creativity and increasing physical activity.”

Exercise Boosts Brain Growth and Regeneration

As mentioned earlier, fascinating research shows that
your brain is capable of rejuvenating and regenerating itself throughout
your life. This information is completely contrary to what I was taught
in medical school. At that time, it was believed that once neurons die,
there’s nothing you can do about it. Hence deterioration and
progressive memory decline was considered a more or less inevitable part
of aging. Fortunately, that’s simply not true.

According to John J. Ratey, a psychiatrist who wrote the book Spark: The Revolutionary New Science of Exercise and the Brain,
there’s overwhelming evidence that exercise produces large cognitive
gains and helps fight dementia. The featured article cites research8 showing
that those who exercise have a greater volume of gray matter in the
hippocampal region of their brains, which is important for memory.
According to the authors:

“After controlling for age, gender, and total brain
volume, total minutes of weekly exercise correlated significantly with
volume of the right hippocampus. Findings highlight the relationship
between regular physical exercise and brain structure during early to
middle adulthood.”

“These results suggest that cardiovascular fitness is
associated with the sparing of brain tissue in aging humans.
Furthermore, these results suggest a strong biological basis for the
role of aerobic fitness in maintaining and enhancing central nervous
system health and cognitive functioning in older adults.”

Similar findings have been found by other scientists. For example, one observational study11 that
followed more than 600 seniors, starting at age 70, found that those
who engaged in the most physical exercise showed the least amount of
brain shrinkage over a follow-up period of three years.

How Does Exercise Affect Brain Power?

One of the mechanisms by which your brain benefits from
physical exercise is via a protein called Brain Derived Neurotrophic
Factor (BDNF). Exercise initially stimulates the production of a protein
called FNDC5, which in turn triggers the production of BDNF. BDNF is a
remarkable rejuvenator in several respects. In your brain, BDNF not only
preserves existing brain cells,12 it also activates brain stem cells to convert into new neurons, and effectively makes your brain grow larger.

Research13 confirming
this includes a study by Kirk Erickson, PhD, in which seniors aged 60
to 80 who walked 30 to 45 minutes, three days per week for one year,
increased the volume of their hippocampus by two percent. The
hippocampus is a region of your brain important for memory. Erickson
told WebMD:14

“Generally in this age range, people are losing one
to three percent per year of hippocampal volume. The changes in the size
of the hippocampus were correlated with changes in the blood levels of
the brain-derived neurotrophic factor (BDNF).”

Erickson also found that higher fitness levels were associated with a
larger prefrontal cortex. He called exercise “one of the most promising
non-pharmaceutical treatments to improve brain health.” Two additional
mechanisms by which exercise protects and boosts your brain health
include the following:

Reducing plaque formation: By altering the way
damaging proteins reside inside your brain, exercise may help slow the
development of Alzheimer’s disease. In one animal study,15 significantly
fewer damaging plaques and fewer bits of beta-amyloid peptides,
associated with Alzheimer’s, were found in mice that exercised.

Decreasing BMP and boosting Noggin:
Bone-morphogenetic protein (BMP) slows down the creation of new neurons,
thereby reducing neurogenesis. If you have high levels of BMP, your
brain grows slower and less nimble. Exercise reduces the impact of BMP,
so that your adult stem cells can continue performing their vital
functions of keeping your brain agile.In animal research,16,17 mice
with access to running wheels reduced the BMP in their brains by half
in just one week. In addition, they also had a notable increase in
another brain protein called Noggin, which acts as a BMP antagonist. So,
exercise not only reduces the detrimental effects of BMP, it
simultaneously boosts the more beneficial Noggin as well. This complex
interplay between BMP and Noggin appears to be yet another powerful
factor that helps ensure the proliferation and youthfulness of your
neurons.

Exercise Prevents Both Brain and Muscle Decay

Showing the interconnectedness between muscle and brain
health, BDNF also expresses itself in the neuro-muscular system where it
protects neuro-motors from degradation. The neuromotor is the most
critical element in your muscle. Without the neuromotor, your muscle is
like an engine without ignition. Neuro-motor degradation is part of the
process that explains age-related muscle atrophy.

So BDNF is actively involved in both your muscles and your
brain, and this cross-connection appears to be a major part of the
explanation for why a physical workout can have such a beneficial impact
on your brain tissue. It, quite literally, helps prevent, and even
reverse, brain decay as much as it prevents and reverses age-related
muscle decay. The most important message from studies like these is that
mental decline is by no means inevitable, and that exercise is as good
for your brain as it is for the rest of your body.

Diet and Fasting Also Plays a Role

Interestingly, fasting and exercise trigger very similar
genes and growth factors that recycle and rejuvenate both your brain and
muscle tissues. These growth factors include BDNF and muscle regulatory
factors (MRFs). These growth factors signal brain stem cells and muscle
satellite cells to convert into new neurons and new muscle cells
respectively. This also helps explain why exercise while fasting can help keep your brain, neuro-motors, and muscle fibers biologically young.

For more information on how to incorporate intermittent fasting into
your exercise routine for maximum benefits, please see my previous
article, “High-Intensity Interval Training and Intermittent Fasting – A Winning Combo.”
Besides the issue of when you eat, what you eat is of great importance.
Sugar suppresses BDNF, which helps explain why a low-sugar diet in
combination with regular exercise is so effective for protecting memory
and staving off depression. Sugar, and fructose in particular, will also
obliterate your body’s production of human growth hormone (HGH) when consumed within two hours after a workout, and HGH production is a major benefit of high intensity interval training (HIIT).

Exercise Can Help Keep You Sharp Well Into Old Age

While it’s never too late to start exercising, the
earlier you begin and the more consistent you are, the greater your
long-term rewards. Having an active lifestyle is really an investment in
your future well-being, both physically and mentally. I believe that,
overall, high-intensity interval training really helps maximize the
health benefits of exercise, while simultaneously being the most
efficient and therefore requiring the least amount of time. That said,
ideally you’ll want to strive for a varied and well-rounded fitness
program that incorporates a wide variety of exercises.

I also strongly recommend avoiding sitting as
much as possible, and making it a point to walk more every day. A
fitness tracker can be very helpful for this. I suggest aiming for 7,000
to 10,000 steps per day, in addition to your regular fitness
regimen, not in lieu of it. The science is really clear on this point:
you do not have to lose your mind with advancing age. Your brain has the
capacity to regenerate and grow throughout the entire human lifespan,
and exercise is perhaps the most potent way to ensure your brain’s
continued growth and rejuvenation.